`O(1)` interview cheat sheet

everything you forgot, retrieved in constant time.

a single-page field guide for technical interviews: languages · principles · patterns · systems · machines that think

lookup(concept)   → O(1)
understand(it)    → O(practice)
explain(it)       → the interview

what lives here

~100 dense cards, one page, zero build step.

layer	contents
syntax	Python · JS/TS · Java · Go · C# · Rust · C++ · PHP, plus side-by-side Rosetta tables
shape	OOP pillars · SOLID · DRY/KISS/YAGNI · code smells · GoF patterns · functional patterns
structure	clean / hexagonal · DDD · CQRS · event sourcing · microservices · anti-patterns
flow	event-driven design · delivery guarantees · outbox · sagas · Kafka & friends · streams
ground	cloud models · AWS/GCP/Azure map · Kubernetes · serverless · IaC · HA/DR
scale	system design loop · napkin math · caching · sharding · consistency · rate limiting
state	SQL · indexes · isolation levels · picking a store · analytics stack · identity resolution
wire	REST · GraphQL · gRPC · HTTP · auth · OWASP · crypto · privacy & GDPR
logic	Big-O · problem→pattern map · templates · DP · graphs · concurrency
signal	ML fundamentals · deep learning · LLMs · prompting · RAG · agents · MCP · LLMOps · the buzzword decoder
self	testing · delivery · observability · RCA · STAR · senior signals

level-aware. On first visit it asks what you're interviewing for (junior · mid · senior · architect) and shows the cards that matter at that level. Skip it to see everything; switch anytime from the header.
search that forgives. Multi-word queries rank cards that match every word first, then fall back to the closest partial matches. Hidden synonyms mean k8s, idor or lora find the right card.
shareable state. The query and level live in the URL: ?q=rag&lvl=s.
keyboard first. / to search, Esc to clear.

open index.html

No framework, no bundler, no dependencies. Just HTML, CSS and a bit of JS.

Found a gap or a wrong claim? Open a PR. Each card is one <article>:

<article class="card" data-lvl="m s a" data-cat="events" data-k="extra search synonyms">

_{syntax is lookup · judgment is the job}